(1) Field of the Invention
The present invention relates to a process and apparatus for the preparation of a synthetic resin vessel having a handle. More particularly, the persent invention relates to a process and apparatus for preparing a synthetic resin vessel having a handle, comprising a vessel proper prepared by blow-forming or draw-blow-forming of a synthetic resin and a handle prepared independently from the vessel proper but secured to the vessel proper, at a high productivity without any loss time.
(2) Description of the Related Art
A plastic hollow vessel has a light weight and an excellent impact resistance. Accordingly, this vessel is widely used as a container for various liquids. Especially, a hollow vessel obtained by blow-draw-forming of polyethylene terephthalate (hereinafter referred to as "PET") has a high transparency, a good gas-barrier property, a light weight, an excellent impact resistance and an appropriate rigidity in combination, and this vessel is widely used as a packaging container for storing a liquid content therein.
In the case of a draw-blow-formed vessel of this type having a large size, in order to facilitate handling, it is desired to attach a handle to the vessel proper. From the principle of the blow-draw-forming process, it is difficult to form a handle integrally with the vessel by draw-blow-forming. Therefore, several proposals have been made on the method of attaching a handle to a draw-blow-formed vessel.
For example, there have been proposed a process in which a handle is formed in advance, the handle is placed in a blow mold, and a vessel-forming preform is draw-blown to prepare a draw-blow-formed vessel having a handle integrated therewith (see Japanese Unexamined Patent Publication No. 56-64948, Japanese Unexamined Patent Publication No. 56-64949 and Japanese Unexamined Patent Publication No. 56-74438), and a process in which a vessel having a handle is prepared by arranging in a rotary a station for forming a vessel parison by an injection unit, a station for draw-blow-forming the parison, a station for arranging an injection mold around the formed vessel, applying a pressure to the interior of the vessel and injection-forming a handle by another injection unit and a station for withdrawing the formed vessel having a handle (see Japanese Unexamined Patent Publication No. 62-182044).
In the case where a handle is formed on a vessel, there is ordinarily adopted a method in which a plurlaity of circumferential grooves are formed around the circumference of the vessel, and a handle is constructed by a plurality of band portions surrounding the circumferential grooves closely thereto and a handle portion formed integrally with the band portions. However, the presence of such band portions is not preferable in view of the appearance characteristics of the vessel. Moreover, molding defects such as burrs and weld marks are readily formed when the band portions are formed around the vessel by injection molding. This method is still insufficient in the effect of fixing the handle to the vessel assuredly and tightly.